In 2000, Suter, et. al., conducted study about Knee-joint pathologies, which particularly anterior knee pain (AKP), are frequently associated with strength deficits and diminished activation of knee extensors, a phenomenon known as muscle inhibition (MI). MI is considered a hindrance to full functional recovery, emphasizing the need for effective rehabilitation strategies. Clinical observations have linked AKP to sacroiliac (SI) joint dysfunction. However, it remains unclear whether SI-joint dysfunction contributes to knee-extensor deficits and if correcting it can alleviate MI.

This study aimed to investigate the impact of conservative lower back treatment on lower limb MI in patients with AKP through a randomized, controlled, double-blind trial.

Twenty-eight patients with AKP were randomly assigned to either a treatment or control group. The treatment group underwent a lower back functional assessment followed by a conservative treatment involving chiropractic spinal manipulation targeting SI-joint dysfunction. The control group received a lower back functional assessment without joint manipulation. Knee-extensor moments, MI, and muscle activation during isometric knee extensions were measured before and after the intervention.

Patients exhibited significant MI in both legs, and all subjects demonstrated SI-joint dysfunction upon functional assessment (23 symptomatic and 5 asymptomatic). Following SI-joint manipulation, the treatment group experienced a noteworthy 7.5% reduction in MI in the affected legs. No significant changes in MI were observed in the contralateral legs of the treatment group or in the legs of the control group. Knee-extensor moments and muscle activation did not show statistically significant changes in either group.

The findings from this study suggest that SI-joint manipulation can effectively decrease knee-extensor MI. Conservative lower back treatment, particularly spinal manipulation, emerges as a potential therapeutic approach for addressing MI in lower limb musculature. Further research is warranted to validate these findings and explore the broader implications for rehabilitation strategies in knee-joint pathologies.

Reference: Suter, E., McMorland, G., Herzog, W., & Bray, R. (2000). Conservative lower back treatment reduces inhibition in knee-extensor muscles: a randomized controlled trial. Journal of Manipulative and Physiological Therapeutics, 23(2), 76-80.